1. Field of the Invention
The invention relates to composite materials based on a hydraulic binder and a reinforcing filler such as those, notably of the asbestos-cement type, which are used in the building industry. More precisely, it relates to materials based on a silica-calcareous hydraulic binder and to their manufacture.
2. Description of the Prior Art
Materials of this type are currently used, for example in the form of plates, tiles or pre-fabricated panels, both as coverings for facades and other walls in the building industry. They are obtained by hardening mixtures containing essentially a hydraulic binder, calcareous or silico-calcareous, a reinforcing filler, constituted generally from mineral and/or organic fibers, namely asbestos most often, and if necessary other fillers or additives. The products preferred among the materials at present known are, at least for outside uses, those for which the constituents of the starting mixtures comprise not only cement and asbestos, but also sand which introduces silica into the final composition. Their hardening, carried out entirely at the manufacturing plant, generally involves treatment in a steam atmosphere, which is carried out mostly in an autoclave, at pressure above atmospheric pressure.
These materials have met with great success. In the covering of facades for example, they play a role which is both protective and decorative. However, extension of their use has been retarded by difficulty in responding, in this double role, to the more and more stringent requirements of users. On the other hand, various treatments, more or less simple or expensive, have been developed to avoid their degradation over time, which is marked by the appearance of efflorescence on the materials exposed to humidity and to bad weather. On the other hand, the manufacture of colored materials by means of industrial pigments runs up against difficulties in obtaining products whose color is homogeneous and reproducible. In addition, the degradation caused by aging is doubled by a certain washing out of the pigment, further accentuating the phenomenon.
It is an object of the present invention to overcome these drawbacks of conventional techniques, by means of a process and a composition which enables the coloration in a mass of the material to be ensured whilst preserving good qualities of resistance to bad weather, the latter being even possibly improved.